Manon Ragonnet-Cronin, Samantha J. Lycett, Emma B. Hodcroft et al.
The Journal of infectious diseases, vol. 213, 1410--1418, 2016
10.1093/infdis/jiv758
Abstract
BACKGROUND: The United Kingdom human immunodeficiency virus (HIV) epidemic was historically dominated by HIV subtype B transmission among men who have sex with men (MSM). Now 50\% of diagnoses and prevalent infections are among heterosexual individuals and mainly involve non-B subtypes. Between 2002 and 2010, the prevalence of non-B diagnoses among MSM increased from 5.4\% to 17\%, and this study focused on the drivers of this change. METHODS: Growth between 2007 and 2009 in transmission clusters among 14 000 subtype A1, C, D, and G sequences from the United Kingdom HIV Drug Resistance Database was analysed by risk group. RESULTS: Of 1148 clusters containing at least 2 sequences in 2007, {\textgreater}75\% were pairs and {\textgreater}90\% were heterosexual. Most clusters (71.4\%) did not grow during the study period. Growth was significantly lower for small clusters and higher for clusters of {\textgreater}/=7 sequences, with the highest growth observed for clusters comprising sequences from MSM and people who inject drugs (PWID). Risk group (P{\textless} .0001), cluster size (P{\textless} .0001), and subtype (P{\textless} .01) were predictive of growth in a generalized linear model. DISCUSSION: Despite the increase in non-B subtypes associated with heterosexual transmission, MSM and PWID are at risk for non-B infections. Crossover of subtype C from heterosexuals to MSM has led to the expansion of this subtype within the United Kingdom.